The FBI is asking property owners in parts of North Dakota and Montana to check vacant farmsteads for signs of disturbed soil where the agency says a Sidney teacher missing since early January might be buried.
Earlier Sunday, authorities released the names of two Parachute, Colo., men being held in a North Dakota jail in connection with the Jan. 7 disappearance of 43-year-old Sherry Arnold of Sidney.
The FBI issued a statement late Sunday saying Arnold's body might be buried in an area with a line of mature or rotted trees, including in shelter belts and on vacant farmsteads, and the surrounding grass might be matted.
The agency requests that North Dakota property owners in Williams, McKenzie and Mountrail counties, and in extreme northeastern Montana, check such areas.
"It is important to note, law enforcement is only requesting help from property owners and is not requesting volunteers to come search," said FBI spokeswoman Debbie Bertram in a news release. "Property owners are advised not to put themselves at risk."
She asked that anybody who discovers "something unusual" not disturb the site and instead call the Williams County, N.D., Law Enforcement Center at 701-774-9191.
Authorities say 47-year-old Lester Vann Waters Jr. and 22-year-old Michael Keith Spell are in the Williams County Correctional Center in Williston, N.D., awaiting extradition to Montana.
Arnold, a well-liked math teacher at Sidney High School, went for an early-morning run on Jan. 7 and never returned home.
Area residents and law enforcement scoured Richland County for days after her disappearance, with the only publicly aknowledged clue being the discovery of one of her shoes along a regular jogging route.
On Friday, authorities announced they had one man in custody in North Dakota and that another was being questioned in South Dakota. The next day, Sidney Police Chief Frank DiFonzo told a Gazette reporter that two men were being held in Williams County, N.D., on suspicion of aggravated kidnapping.
Until Sunday, authorities did not confirm if they had recovered Arnold's body but did say after the arrests that there was an ongoing search.
"Based on investigative evidence gathered over the last few days, it is believed that Ms. Arnold may be deceased; her body has not been recovered," Bertram said in the news release.
The FBI joined the investigation mid-week and a few days later, an anonymous tip led investigators to the two men. Officials have not, however, said how or exactly when and where they were arrested. They were brought to the jail in Williston on Friday.